The Hedgehog (Hh) signaling pathway is crucial for vertebrate embryonic development, tissue homeostasis and regeneration. Hh signaling is upregulated in basal cell carcinoma and medulloblastoma and Hh pathway inhibitors targeting the Smoothened (SMO) protein are in clinical use. However, the signaling cascade is incompletely understood and novel druggable proteins in the pathway are in high demand. We describe the discovery of the Hh-pathway modulator Pipinib by means of cell-based screening. Target identification and validation revealed that Pipinib selectively inhibits phosphatidylinositol 4-kinase IIIβ (PI4KB) and suppresses GLI-mediated transcription and Hh target gene expression by impairing SMO translocation to the cilium. Therefore, inhibition of PI4KB and, consequently, reduction in phosphatidyl-4-phosphate levels may be considered an alternative approach to inhibit SMO function and thus, Hedgehog signaling.
- Klíčová slova
- Hedgehog signaling, PI4KB, biological activity, inhibitors,
- MeSH
- buněčné linie MeSH
- cilie metabolismus MeSH
- exprese genu účinky léků MeSH
- fosfotransferasy s alkoholovou skupinou jako akceptorem antagonisté a inhibitory genetika metabolismus MeSH
- lidé MeSH
- malá interferující RNA metabolismus MeSH
- morfoliny farmakologie MeSH
- myši MeSH
- osteogeneze účinky léků MeSH
- proteiny hedgehog antagonisté a inhibitory genetika metabolismus MeSH
- protinádorové látky chemie farmakologie MeSH
- puriny farmakologie MeSH
- receptor Smoothened genetika metabolismus MeSH
- RNA interference MeSH
- signální transdukce účinky léků MeSH
- thiofeny chemie farmakologie MeSH
- vedlejší histokompatibilní antigeny genetika metabolismus MeSH
- viabilita buněk účinky léků MeSH
- vztahy mezi strukturou a aktivitou MeSH
- zvířata MeSH
- Check Tag
- lidé MeSH
- myši MeSH
- zvířata MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
- přehledy MeSH
- Research Support, N.I.H., Extramural MeSH
- Názvy látek
- fosfotransferasy s alkoholovou skupinou jako akceptorem MeSH
- malá interferující RNA MeSH
- morfoliny MeSH
- phosphatidylinositol phosphate 4-kinase MeSH Prohlížeč
- proteiny hedgehog MeSH
- protinádorové látky MeSH
- puriny MeSH
- purmorphamine MeSH Prohlížeč
- receptor Smoothened MeSH
- thiofeny MeSH
- vedlejší histokompatibilní antigeny MeSH
Despite the simplicity of the molecule, the site of single deprotonation of p-hydroxybenzoic acid upon electrospray ionization (ESI) has recently formed a subject of debate in this journal. By means of NMR experiments in solution and gas-phase studies employing ion-mobility mass spectrometry (IM-MS), the apparent controversy is resolved. It is shown that irrespective of the solvent the carboxylate tautomer is preferred in solution, while the opposite holds true for isolated ions in the gas phase. The tautomer distribution sampled in the gas phase very much depends on the actual solvent used in ESI, the pH value, as well as the total concentration. Moreover, the occurrence of gas-phase reactions in the course of the ESI process influences the tautomer ratio. Implications for correlations between ESI mass spectra and solution-phase chemistry are discussed.
- Publikační typ
- časopisecké články MeSH
Oligo-Tröger bases are auspicious scaffolds of molecular engineering, which motivates studies on the mechanism of their interconversion and on the facile determination of the relative configuration of their diastereoisomers. Protonated, sodiated, and argentated species of those compounds were therefore studied via ion-mobility mass spectrometry (IM-MS), allowing differentiation on the basis of the shapes of the ions. First, the isomerization was confirmed to be acid-catalyzed as it takes place readily in the case of protonated Tröger bases, whereas the metallated bases are configurationally stable. Second, the corrected arrival times of the various isomers of the cationized bases were found to show distinct differences in IM-MS, and their excellent correlation with the cross sections obtained from quantum chemical calculations paves the way toward the easy identification of diastereoisomers.
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
Electrospray ionization is suggested as a complementary technique for the investigation of the solution chemistry of metal salts, which allows us to achieve direct insight into the molecular entities present in solution. While the transfer of the metal ions from solution to the gas phase in the course of the electrospray process is associated with significant changes in concentration, pH, and also composition in the case of mixed solvents, systematic studies of concentration series can provide criteria to assess the extent to which the gas-phase data correlate with the situation in solution. While there does not exist a 1 ∶ 1 correlation between mass spectrometric measurements and solution properties, very useful qualitative molecular insights can be achieved and quantitative analysis can be made once the specific circumstances of the ionization process are taken into account.
- Publikační typ
- časopisecké články MeSH
Benzylpyridinium ions, generated via electrospray ionization of dilute solutions of their salts in acetonitrile/water, are probed by collisional activation in an ion-trap mass spectrometer. From the breakdown diagrams obtained, phenomenological appearance energies of the fragment ions are derived. Comparison of the appearance energies with calculated reaction endothermicities shows a reasonably good correlation for this particular class of compounds. In addition, the data indirectly indicate that at threshold the dissociation of almost all of the benzylpyridinium ions under study leads to the corresponding benzylium ions, rather than the tropylium isomers. Substituent effects on the fragmentation for a series of benzylpyridinium ions demonstrate that neither mass effects nor differences in density of states seriously affect the energetics derived from the ion-trap experiments.
- Publikační typ
- časopisecké články MeSH
Electrospray ionization of dilute aqueous solutions of copper(II) chloride-containing traces of pyridine (py) as well as ammonia permits the generation of the gaseous ions (py)(2) Cu(+) and (py)(2) CuCl(+) , of which the latter is a formal copper(II) compound, whereas the former contains copper(I). Collision-induced dissociation of the mass-selected ions in an ion-trap mass spectrometer (IT-MS) leads to a loss of pyridine from (py)(2) Cu(+) , whereas an expulsion of atomic chlorine largely prevails for (py)(2) CuCl(+) . Theoretical studies using density functional theory predict a bond dissociation energy (BDE) of BDE[(py)(2) Cu(+) -Cl] = 125 kJ mol(-1) , whereas the pyridine ligand is bound significantly stronger, i.e. BDE[(py)CuCl(+) -py] = 194 kJ mol(-1) and BDE[(py)Cu(+) -py] = 242 kJ mol(-1) . The results are discussed with regard to the influence of the solvation on the stability of the Cu(I) /Cu(II) redox couple.
- Publikační typ
- časopisecké články MeSH
The "bare" complex [Cu(PhOH)(PhO)](+) with a phenol (PhOH) and a phenoxy (PhO) ligand bound to copper is studied both experimentally and computationally. The binding energies and structure of this complex are probed by mass spectrometry, infrared multi-photon dissociation, and DFT calculations. Further, the monoligated complexes [Cu(PhO)](+) and [Cu(PhOH)](+) are investigated for comparison. DFT calculations on the [Cu(PhOH)(PhO)](+) complex predict that a phenolate anion interacts with copper(II) preferentially through the oxygen atom, and the bonding is associated with electron transfer to the metal center resulting in location of the unpaired electron at the aromatic moiety. Neutral phenol, on the other hand, interacts with copper preferentially through the aromatic ring. The same arrangements are also found in the monoligated complexes [Cu(PhO)](+) and [Cu(PhOH)](+). The calculations further indicate that the bond strength between the copper atom and the oxygen atom of the phenoxy radical is weakened by the presence of neutral phenol from 2.6 eV in bare [Cu(PhO)](+) to 2.1 eV in [Cu(PhOH)(PhO)](+).
- MeSH
- fenoly chemie MeSH
- galaktosaoxidasa chemie metabolismus MeSH
- hmotnostní spektrometrie s elektrosprejovou ionizací MeSH
- kationty MeSH
- kvantová teorie MeSH
- měď chemie MeSH
- metaloproteiny chemie metabolismus MeSH
- molekulární modely MeSH
- spektrofotometrie infračervená MeSH
- termodynamika MeSH
- vazebná místa MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
- Názvy látek
- fenoly MeSH
- galaktosaoxidasa MeSH
- kationty MeSH
- měď MeSH
- metaloproteiny MeSH
- phenoxy radical MeSH Prohlížeč
The solvation of copper(II) sulfate in binary mixtures of water and N,N-dimethylformamide (DMF) is studied by a combined approach using electrochemical studies in solution and a mass spectrometric assay of the solvated ions formed from these solutions upon electrospray ionization (ESI). In the condensed phase, the limiting transference numbers (t(+/-)(o)) and the apparent ion association constants (K(A)'s) of CuSO(4) have been determined in water/DMF solutions at 20 degrees C. The t(+)(o) values decrease with increasing DMF content, demonstrating a gradual solvation of Cu(2+) by DMF molecules. The association constants indicate that aggregation becomes more pronounced as the DMF content increases. In order to achieve complementary insight, the intrinsic interactions among the ions and solvent molecules are investigated in gas-phase experiments of the CuSO(4)/water/DMF system using ESI mass spectrometry. Under the conditions used, the dications [Cu(DMF)(n)](2+) (n = 3-6), [Cu(2)(DMF)(n)SO(4)](2+) (n = 2-7), and [Cu(3)(DMF)(n)(SO(4))(2)](2+) (n = 2-7), and the monocations [Cu(OH)(DMF)(n)](+), [Cu(DMF)(n)(HSO(4))](+) (both, n = 1-3), and [Cu(DMF)(n)](+) (n = 1, 2), are formed as the leading copper-containing cations. Likewise, polynuclear copper clusters observed in the anion ESI spectra support partial aggregation occurring in solution. The gas-phase studies clearly support the conclusions that (i) DMF is a highly preferred ligand for CuII in comparison to water and that (ii) DMF supports ion association for which the mass spectrometric data suggest the formation of polynuclear copper clusters.
- Publikační typ
- časopisecké články MeSH
Electrospray ionization from methanolic solution can be used for the generation of the free cyclophane tetracations 1(4+) -3(4+) from the corresponding hexafluorophosphates. In the idealized gas phase, these tetracations are long-lived and can easily be handled for further spectroscopic studies. Collision-induced dissociation of the free tetracations brings about charge separation via cleavage of the pyridinium bonds, leading to a pair of dications. Subsequently, these dications undergo another charge separation reaction to finally afford singly charged cations. In addition to the free tetracations, also the corresponding trications having one PF6- counterion are examined. Collision-induced dissociation of the trications leads to a formal substitution reaction concomitant with C-F bond formation. Further, the catenanes of the tetracations 1(4+) -3(4+) with bis-p-phenylene-34-crown-10 (4) are investigated. For the parent compound 1, also the gas-phase infrared spectrum is reported for the first time.
- Publikační typ
- časopisecké články MeSH
The bimolecular reactions of several hydrocarbon dications C(m)H(n)(2+) (m = 6-10, n = 4-9) with neutral benzene are investigated by tandem mass spectrometry using a multipole instrument. Not surprisingly, the major reaction of C(m)H(n)(2+) with benzene corresponds to electron transfer from the neutral arene to the dication resulting in the pair of monocationic products C(m)H(n)(+) + C(6)H(6)(+). In addition, also dissociative electron transfer takes place, whereas proton transfer from the C(m)H(n)(2+) dication to neutral benzene is almost negligible. Interestingly, the excess energy liberated upon electron transfer from the neutral arene to the C(m)H(n)(2+) dication is not equally partitioned in the monocationic products in that the cations arising from the dicationic precursor have a higher internal energy content than the monocations formed from the neutral reaction partner. In addition to the reactions leading to monocationic product ions, bond-forming reactions with maintenance of the two-fold charge are observed, which lead to a condensation of the C(m)H(n)(2+) dications with neutral benzene under formation of intermediate C(m+6)H(n+6)(2+) species and then undergo subsequent losses of molecular hydrogen or neutral acetylene. This reaction complements a recently proposed dicationic route for the formation of polycyclic aromatic hydrocarbons under extreme conditions such as they exist in interstellar environments.
- MeSH
- benzen chemie MeSH
- elektrony MeSH
- hmotnostní spektrometrie metody MeSH
- kationty chemie MeSH
- oxidace-redukce MeSH
- senzitivita a specificita MeSH
- uhlovodíky chemie MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
- Názvy látek
- benzen MeSH
- kationty MeSH
- uhlovodíky MeSH
